Rise of the Phoenix

iTrader: (27)

Spanks13, I hope you do a build thread on here. I'm looking forward to seeing how this combo works out for you with the Haymaker heads being the centerpiece of this awesome build.

carbuff

iTrader: (8)

Technically a carb-style manifold with EFI if you want to get picky about it. But correct, not a traditional LS-style intake.

I'm curious: when people quote the E/I relationship, do they do it at a particular lift number? I just calculated mine for my FRH heads, and from 0.2 to 0.7, it varies from 65% to 72%:

0.2 71.6%
0.3 68.6%
0.4 72.4%
0.5 68.1%
0.6 65.6%
0.7 65.4%

Average 68.6%

I've had 2 cams in this motor, both happened to have 10* splits, specified by 2 different sources. Not saying it's right or wrong, just sharing more data.

spanks13

iTrader: (5)

Thanks! Made 468/451 with stock LS3 heads, intake, and hooker exhaust manifolds to full length 2.5". Car weighs 2850. Backed it up with a 11.40@129.80mph run in road race trim.

It's going to be fast

I'm limited on intake choice due to engine bay and hood fitment. Would loveeee a mid length runner Fast but I'm not going to happen.

https://www.youtube.com/watch?v=7ouQ...ature=youtu.be

Rise of the Phoenix

iTrader: (27)

Can you go into more detail on what the GPI "rod mod" LS3 intake is?

Very nice car. That light little thing is going to be flying with the new mods.

spanks13

iTrader: (5)

Thanks! It is the Rick Crawford mod performed by GPI. They don't do some of the porting that Rick does, but have core exchange intakes on the shelf and claim the radius rods are 90% of the gains which I could believe. Also, cutting out the posts in the intake sometimes can lead to odd noises at part throttle which is not cool.

I swapped the intake already I had to pull timing to get it to stop pinging with my old calibration and also add fuel to areas of the calibration, especially upstairs. No dyno results, but seems to be doing good things.

http://www.camaro5.com/forums/showthread.php?t=344234

Rise of the Phoenix

iTrader: (27)

Very interesting. Thanks for sharing.

JakeFusion

iTrader: (7)

Well, talk to a few different cam guys. And look at some of the fastest cars. And what do you find?

A good rule of thumb for most street engines is if the I/E ratio is 75% you need a single pattern cam at .050". If for every % below that you need about 1.5 degrees of split favoring the exhaust. For every % above that you need to add 1.5 Degrees to the intake.

So a 68.6% I/E ratio ends up being around a 9.6 degree split... or the 10 degrees you saw.

If you do not have enough exhaust duration and you add exhaust and open your exhaust valve earlier... you will pick up power. If you are already optimized and you keep opening sooner and sooner, you will overscavenge and make less overall power. But your peak power may continue to go up.

I don't really know what the TFS 255 heads flow. TEA exhaust numbers are inflated. Otherwise, it shows I/E ratio of about 74% which means it needs almost no split.

And just to throw that out there, my TEA Stage 2s have an avg I/E of 82% going by the flow numbers TEA gave me. Which means I'd need 10 degrees more intake if I were going to do a split... I don't think that would work as well as say the 234/242 I had in the car. If I did a 244/234? It would make more torque and would peak at 6300. And then it would fall off immediately. So it make for an interesting road race engine.

A.R. Shale Targa

iTrader: (2)

I'd think it's pretty important to look at E/I ratio using the exhaust numbers with a pipe as most (95%) are running headers which generally ups the Ex. flow about 20 cfm or so

Tuskyz28

A guy that specs cam told me on the phone the less split cams tend to run the fastest/faster times at the track vs a cam with a wide split such as 235/250 cam (15 degree split).

JakeFusion

iTrader: (7)

Yeah, I've heard that before. Unfortunately, that 75% I/E for a single pattern split is generally done without a pipe. Since the exhaust flow numbers are inflated so much with them.

But this is why it's hard to base things off of flow numbers. They can be inflated anyway you want. You can look at the flow and spec the cam. Then run it. Then spec the cam a little different for the same motor. And run that. And see what goes faster. A good shop has taken a shop car, built a combo for it, and has probably done that. Then when you go to them, they have the dynos and the track data to support their cam profiles in that configuration.

And the point on the tighter I/E split depends on what you're doing with the motor. If you are running a single plane intake, then you can move the IVC up as high as you can so you peak higher for the track. Then you don't have extended the EVO earlier and earlier to keep holding past peak. You can control it more with the IVC and the intake design. At that point a 4-6 degree split would be fine.

spanks13

iTrader: (5)

With a single plane you want a very tight center, 106 -108 cam with a very early IVC to recover some dynamic compression due to increased overlap of the tight centers. With a late IVC the worst case is the intake charge stalls out and you push all that air back out the intake valve as the piston is coming back up.

Because the column of air is so small the short runner has little intertia compared to a long intake runner and the ram charging effect is minimal after the piston reaches BDC and starts reversing upward. Short runner single planes work more based on velocity and all out flow potential vs intertia filling the cylinder.

JakeFusion

iTrader: (7)

You still IVC it properly for the intended RPM. Depending on the intake, that might mean reducing the IVC or increasing it from a plastic intake for the same RPM range. And then it depends on the length of the runners, etc. The shorter runners typically need more overlap which helps with the inertia issue.

For example a 234/242 111+3 I had worked well with the FAST 102. IVC of 45. EVO of 55. 16 degrees of overlap. Designed to make high RPM power.

Had I switched to a singe plane and wanted to make more power everywhere, I would have done a 242/250 107+3. Same IVC and EVO. But 32 degrees of overlap. Would have made more power and extended the RPM range a bit. But it would have been a track only type of deal in a 346. You just have to add a shitload of overlap to it for it to perform correctly and make the torque you want.

NAVYBLUE210

Spanks13
Really looking forward to your build and results, If those flow #s are even
close to posted your 242*/248* cam specs will be excellent! I would probably
go 114*+3* for LSA but that is just splitting hairs LOL.

More critical I would strongly encourage the Straub or CHE Bushings
vs the needle trunion upgrade. Also I have been told .630" is about
the lift limit with the stock rockers. I would limit lift to .625" with
the stock rockers for durability. Can always go stud-mount for
.680-.700" lift down the road if/when you want/need more .
Engine will be a beast in your RX7!

spanks13

iTrader: (5)

Thanks Navyblue!

I forgot to mention..there's a superflow bench in my garage and will post up some numbers on a 4" bore when I receive the heads. I can compare them against stock LS3 and LPE CNC ported LS3 heads.

It is going to be interesting to see what the sweep pattern is like with factory rockers with the longer valves. They're .550" longer than stock. I'd imagine that'd improve the situation.

And yes..I just saw the comp cams trunion thread and I'm not too thrilled. I'm not a fan of aluminum roller rockers due to the weight which really limits choices to crower stainless which are $$$$$ or replacing the trunions with CHE which we have in another engine and are working great. The crower rockers would be a great way to take advantage of the taller installed height and get some good lift in there, but scope creep is getting a little out of hand at that point.

carbuff

iTrader: (8)

Interesting... We have somewhat derailed this thread, but I like the conversation.

I'm in the process of assembling a different combination, and I'm very curious to see how it turns out. It goes against Jake's (and others) recommendation of tightening the LSA for a single plane. I have a good baseline to compare against, so once I have the results, I'll be curious to see what I get.

Using the head data I quoted above, the cam speced for me is 252/266 at 114+4. It's a solid roller, and I'm told in this case to remove 6* for HR comparison, so let's call it 246/260. Still a 14* split. It's larger in all dimensions than my current cam, slightly shifted towards the close timing on both intake and exhaust. It's a relatively large overlap at 25* compared to my current 21*.

I'm leaning towards putting this on an engine dyno when it's built. I've never done that before, and I have a convenient opportunity to do so with this build. I will certainly share the results if that happens, along with chassis dyno numbers down the road...

carbuff

iTrader: (8)

Was it ever stated which castings these heads start out as? Does Crower make a rocker setup for them? I have the Crowers on my current heads, and while pricey, they are a very nice setup...

JakeFusion

iTrader: (7)

The Straubs are nice.

I plan to install mine this weekend. But I have some other things going on.

I'll see how the Comp trunnions look.

Also plan to switch over to the Joe Gibbs LS30 oil. Was running VR1, then I had an incident and had to put some oil that I had on hand in. Castrol Syntec. So I want to go back to a more ZDDP and higher PSI oil. The LS30 is a little better than the VR1 in all regards and has better detergents in it as well. So better for the street.

And yes, would like to know the original casting. That would help.

The Crowers even come with bushed rollers as an upgrade.

The T&D are also nice.

Rise of the Phoenix

iTrader: (27)

I'll try to find out what casting is used.

Martin Smallwood

iTrader: (2)

You guys do realize that you will never be able to simulate the pressure in the exhaust port on a running engine with a flow bench at 28"?

I know some very well known people that won't even flow their exhaust ports...

NAVYBLUE210

So does that mean E/I relationships like LSA Doesn't Matter?